- Moved abs_def to drule.ML
- elim_defs now takes a boolean argument which controls the automatic
expansion of theorems mentioning constants whose definitions are
eliminated
consts sep :: "'a * 'a list => 'a list"
recdef sep "measure (%(a,xs). length xs)"
"sep(a, []) = []"
"sep(a, [x]) = [x]"
"sep(a, x#y#zs) = x # a # sep(a,y#zs)"